Let $f(x) = 2^x.$ Find $\sqrt{f(f(f(f(1))))}.$
f(1)=2
f(2)=2^2=4
f(4)=2^4=16
f(16)=2^16
if you take the square root of 2^16, the answer is 2^(16/2)=2^8=16^2=256
